Monoetherified products obtained through monoetherification of hydroquinone compounds are useful, for example, as production intermediates for polymerizable compounds.
Examples of conventional methods for monoetherification of hydroquinone compounds include a method disclosed in NPL 1 and 2 in which a hydroquinone compound and an alkyl halide, or the like, are reacted in the presence of a base in a hydrophilic solvent such as water, an alcohol, acetone, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide.
However, there is a problem in terms that when monoetherification of a hydroquinone compound has been attempted using reaction conditions described in NPL 1 and 2, it has not been possible to obtain the target monoetherified product with high yield and high purity.
PTL 1 proposes a method for solving this problem by reacting a dihydroxy compound and a specific etherifying agent in a two-phase system of water and an organic solvent that is substantially water-insoluble to carry out monoetherification of the dihydroxy compound. Moreover, PTL 1 explains that the reaction conversion rate is improved by adding a solvent (cosolvent) that is miscible with both water and the organic solvent to the two-phase system.
However, when a hydroquinone compound and a hydroxyl group-containing etherifying agent are reacted under reaction conditions described in PTL 1, there are cases in which a large amount of a dietherified product of the hydroquinone compound is produced as a by-product and it is difficult to obtain the target monoetherified product in high purity.
The present patent applicant conducted diligent investigation in relation to etherification reactions using hydroquinone compounds and hydroxyl group-containing etherifying agents, and thereby discovered that a monoetherified product can be produced with high yield and high purity by reacting a hydroquinone compound and a hydroxyl group-containing etherifying agent in a two-phase system including an alkaline aqueous solution and a hydrophobic organic solvent (for example, refer to PTL 2).
However, in order to enable even more efficient production of a polymerizable compound, there has been demand for a method by which a monoetherified product that serves as a production intermediate for the polymerizable compound can be obtained with even higher purity and greater efficiency.